Related Experiment Video
Updated: Apr 16, 2026
10:16
Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
9.2K
Population-Specific Circadian Drivers and MTNR1B Predict Arctic Morning Cortisol.
Denis Gubin1,2,3, Sergey Kolomeichuk4,5,6, Konstantin Danilenko1,7
1Laboratory for Chronobiology and Chronomedicine, Research Institute of Biomedicine and Biomedical Technologies, Medical University, Tyumen, Russia.
Summary
Cortisol levels in Arctic residents are influenced by the timing of daily activities and light exposure. Genetic factors, specifically the MTNR1B polymorphism, also play a role in modulating these cortisol responses.
Area of Science:
- Chronobiology
- Human Physiology
- Arctic Research
Background:
- The Hypothalamic-Pituitary-Adrenal (HPA) axis, regulated by cortisol, is sensitive to environmental cues.
- Circadian rhythms are crucial for physiological regulation and can be disrupted by extreme environments like the Arctic.
- The MTNR1B gene polymorphism (rs10830963) has been linked to metabolic and circadian phenotypes.
Purpose of the Study:
- To investigate the relationship between morning cortisol concentration and the circadian timing of physical activity, light exposure, and sleep in Arctic residents.
- To examine the influence of the MTNR1B rs10830963 polymorphism on this relationship.
- To explore population-specific differences (Indigenous vs. Non-Indigenous) in these associations.
Main Methods:
- 7-day actigraphy with RGB light sensors was used to derive circadian parameters.
- Cortisol levels and actigraphy data were collected longitudinally across different seasons (winter solstice, summer solstice, spring equinox).
- Statistical analyses included correlation, regression, and two-way ANOVA, stratified by indigeneity and adjusting for relevant covariates.
Main Results:
- Later timing of physical activity, light exposure, and bedtime were significantly associated with higher morning cortisol concentrations.
- Non-Indigenous participants were primarily influenced by light exposure timing, while Indigenous participants showed associations with activity and sleep timing.
- The MTNR1B rs10830963 genotype modulated cortisol levels, with G-allele carriers exhibiting lower concentrations.
Conclusions:
- Cortisol in Arctic residents is linked to circadian behavior timing, with distinct drivers for Indigenous and Non-Indigenous populations.
- Non-Indigenous individuals integrate both photic and behavioral cues, whereas the Indigenous population relies more on behavioral rhythms.
- The MTNR1B polymorphism further modulates cortisol, highlighting the interplay between environmental timing and genetic background in regulating HPA axis activity in extreme photic environments.
Related Concept Videos
02:19Circadian Rhythms and Gene Regulation
4.7K
The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent...
4.7K
02:19Circadian Rhythms and Gene Regulation
2.5K
2.5K
01:15Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response
488
Circadian rhythms are cyclic changes that are crucial in plasma drug concentrations. Various standard circadian parameters, including core body temperature, heart rate, and other cardiovascular factors, directly impact disease states and the therapeutic response to drug therapy.
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
488
02:45Biological Clocks and Seasonal Responses
42.1K
The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.
42.1K